之前一直运行正常的xaml突然不能运行了，总是显示如下错误。

The test caught an unhandled exception. Caught: System.Activities.InvalidWorkflowException: The following errors were encountered while processing the workflow tree: 'DynamicActivity': The private implementation of activity '1: DynamicActivity' has the following validation error: Compiler error(s) encountered processing expression "XXXXXXX". Type 'XXXXXX' is not defined. '

后来发现mva:VisualBasic.Settings 默认为{x:null}, 将其改为”mva:VisualBasic.Settings="Assembly references and imported namespaces serialized as XML namespaces" 后一切正常。